1. Field of the Invention
The present invention provides an artificial root for dental implantation and a method for manufacturing the artificial root. In particular, the present invention provides an artificial root for dental implantation with parametrically varied threads and a method for manufacturing the artificial root.
2. Descriptions of the Related Art
There are two stages in the growth of human teeth. Specifically, the permanent teeth, which are firmer and more solid, will come out after the baby teeth been extracted. Unlike baby teeth, permanent teeth cannot be reproduced, and can only be repaired or completely removed if the tooth is seriously damaged. The damage or absence of the tooth not only causes defects in the appearance, but may also cause dislocation of the adjacent teeth, resulting in chewing and speaking difficulty. To restore the appearance and improve chewing and speaking, patients often visit the dentist to repair or extract the damaged tooth.
In the dental technology field, tooth caps and bridges are conventionally used to repair teeth or consolidate intertooth structures. The method utilizes the two adjacent teeth as pillars for supporting the crown and the bridge. However, this method may negatively affect the healthy adjacent teeth. For example, two adjacent teeth have to be cut, ground or shaved down to accommodate the tooth caps and bridges that will be disposed therebetween. As a result, the two otherwise healthy teeth are compromised during this process.
With the advancement of science and technologies, dental implantation technology has also been developed. Specifically, an artificial tooth root is implanted directly into an alveolar bone to completely replace the damaged tooth. Since the artificial dental implantation requires no additional devices and support from adjacent teeth, it is less likely to damage adjacent natural teeth and may prevent atrophy of the alveolar bone and the gum, thus maintaining the long-term health and functions of the oral cavity.
In 1950, a Sweden Professor Per-Ingvar Branemark discovered that titanium has great biocompatibility with the human body. That is, there is a lower chance for the human body to reject the titanium, allowing the bone tissue to grow on and integrate on the surface of titanium. Therefore, P-I Branemark proposed the concept of osseointegration and applied the concept into the dental field, thereby making a breakthrough in denture technology.
Due to the progression of science, the denture technology has also becoming more advanced and reliable. The denture process nowadays is carried out by implanting an artificial root with a titanium surface into the alveolar bone where the tooth is extracted. When the artificial root has been implanted, one of conventional treatments is to temporarily stitch up the opening of the gingiva. It may take about three to six months for the osseointegration of the alveolar bone and the artificial root. After the osseointegration is complete and the newly grown bone tissue is tightly integrated with the titanium, the gingivae will be reopened and an abutment will be fixed onto the artificial root. A crown will be further installed on the abutment as the last step in replacing the damaged tooth.
Because the artificial denture does not require the bridge to connect to adjacent teeth as support, the adjacent teeth do not have to be cut, ground and damaged. In addition, there is no atrophy in the alveolar bone and gingivae. To maintain oral health and proper function of the teeth, restoring lost portions of teeth with the implantation of artificial dentures has become increasingly popular.
However, there are still risks in the denture process. When the bone tissue is growing and integrating onto the surface of the artificial root, the micro-motion therebetween should be prevented. The micro-motion may cause the bone tissue to loosen from the surface of the artificial root, causing a failure in osseointegration.
To increase the securing effect and prevent the osseointegration failure, conventional artificial denture roots are disclosed with threads formed on the surface thereof, so that the denture process is carried out by threading the artificial root into the alveolar bone. By this configuration, the artificial root and the alveolar bone can be tightly engaged with each other with the mechanical force provided by the thread in the early stage of the osseointegration, thereby preventing the micro-motion and facilitating the integration of the bone tissue on the surface of the artificial root. Thus, after the denture process is completed, the integration between the alveolar bone and the artificial root relies not only on the surface bonding force therebetween but also relies on the engaged mechanical force to achieve better integration. The artificial root with the thread formed thereon is therefore able to sustain chewing force.
The thread profile of an artificial root is very different from the thread that is commonly seen in other technical fields. A common thread will experience a less tightening force after the initial groove has been formed by the thread during the threading process. However, to better secure the artificial root implantation in the alveolar bone, the thread profile thereof is often specially designed so that the tightening force is increased during the threading process.
The conventional thread structures focus on increasing the lateral force to provide more security. An example of increasing lateral force is to increase the height of the thread that engages with the alveolar bone so that it is deeper during the artificial root implantation. However, the lateral force does not provide enough resistance from micro-motion. In addition, the variation of thread may cause excessive heat in the bone tissue due to a greater tightening force and greater fiction between the alveolar bone and the surface of the artificial root during the threading process. When the bone tissue is heated up over a temperature of 47 Celsius degrees, the cells of the bone tissue will be permanently damaged and the denture implantation will fail. On the other hand, if the artificial root is threaded with a lower speed into the alveolar bone to reduce the generated heat, the surgery time will be prolonged and cause the patient to be uncomfortable for a longer period of time.
Furthermore, if the conventional artificial root is designed in a thread with varied thickness, a plurality of cutting tools should be utilized during manufacture. The varied thread manufactured by various cutting tools is not able to be smooth.
In view of this, it is highly desirable in the art to provide an artificial root with a thread profile in a way that facilitates the implantation and provides more security and faster patient recovery after the surgery. In addition, a novel manufacturing method for making the artificial root is desired.